Several types of technical yarns exist. For example, document U.S. Pat. No. 4,777,789 describes a yarn consisting of an inner core formed by a single or multi-filament, on which an inner yarn is superposed, for example made of stainless steel. The core and the inner yarn are covered with a first yarn wound in a first winding direction which forms a first covering layer; the first covering layer is covered with a second yarn wound in a second winding direction which forms a second covering layer.
Further examples of yarn are described in documents EP1486595A1 and U.S. Pat. No. 4,495,760A.